1. Field
The invention relates to fuel cells having perforated flow fields.
2. Discussion
A fuel cell is an electrochemical conversion device that produces electricity from a fuel and oxidant that react in the presence of an electrolyte.
Referring now to FIG. 1, a prior art fuel cell 10 includes a membrane electrode assembly (MEA) 12 sandwiched between a pair of flow-field plates 14, 16. The MEA 12 includes a proton exchange membrane (PEM) 18 and catalyst layers 20, 22 bonded to opposite sides of the PEM 18. The MEA 12 further includes gas diffusion layers 24, 26 (anode, cathode respectively) each in contact with one of the catalyst layers 20, 22. As apparent to those of ordinary skill, the gas diffusion layer 24 and catalyst layer 20 may collectively be referred to as an electrode. Likewise, the gas diffusion layer 26 and catalyst layer 22 may also collectively be referred to as an electrode.
The flow-field plate 14 includes at least one channel 28n. As known in the art, the at least one channel 28n may form a spiral, “S,” or other shape on the face of the flow-field plate 14 adjacent to the anode 24. Hydrogen from a hydrogen source (not shown) flows through the at least one channel 28n to the anode 24. The catalyst 20 promotes the separation of the hydrogen into protons and electrons. The protons migrate through the PEM 18. The electrons travel through an external circuit 30 to produce electrical power.
The flow-field plate 16 also includes at least one channel 32n. Similar to the at least one channel 28n, the at least one channel 32n may form a spiral, “S,” or other shape on the face of the flow-field plate 16 adjacent the cathode 26. Oxygen from an oxygen or air source (not shown) flows through the at least one channel 32n and to the cathode 26. The hydrogen protons that migrate through the PEM 18 combine with the oxygen and electrons returning from the external circuit 30 to form water and heat.
As apparent to those of ordinary skill any number of fuel cells 10 may be combined to form a fuel cell stack (not shown). Increasing the number of cells 10 in a stack increases the voltage output by the stack. Increasing the surface area of the cells 10 in contact with the MEA 12 increases the current output by the stack.